memory bandwidth hbm

High Bandwidth Memory (HBM) in advanced packaging context refers to the 3D stacked DRAM technology that uses through-silicon vias and micro-bumps to connect multiple memory dies vertically, then integrates the memory stack with logic dies through silicon interposers for extreme bandwidth. HBM stacks 4-12 DRAM dies (each 2-4GB) on a base logic die containing TSVs and interface circuits. The stack uses TSVs for vertical connections and micro-bumps to connect to the interposer. Each HBM stack provides 8-16 independent channels with 1024-bit total interface width, achieving 460-819 GB/s bandwidth per stack (HBM2E/HBM3). Multiple HBM stacks can be placed around a GPU or accelerator die on a shared interposer, providing multi-TB/s aggregate bandwidth. The wide interface and short interconnects (through interposer) enable high bandwidth at low power compared to GDDR memory. HBM is essential for AI training accelerators, high-performance GPUs, and network processors where memory bandwidth is the primary bottleneck. The technology requires advanced packaging (CoWoS, EMIB) and known-good-die testing. HBM represents the convergence of 3D memory stacking and 2.5D heterogeneous integration.